1. Field of the Invention
The present invention relates to a method of producing a compression preservation bag, and more particularly to a method of producing a compression preservation bag having, in an opening portion of a bag part, a closing means such as a fastener or a chuck having convexities and concavities which can engage each other.
2. Description of the Prior Art
Examined Japanese Patent Publication No. 64-10178 discloses a method of automatically and successively producing a bag 1 provided with a chuck.
The method is described below with reference to FIGS. 12 and 13. Initially, a chuck 3 having male and female sides 3a and 3b engaging each other is successively inserted between two rectangular belt-shaped bag-forming films 2a and 2b. Concurrently, as shown in FIG. 13, an insertion tape 4 having one surface with heat-sealing property is inserted between the male side 3a and the female side 3b such that the insertion tape 4 is disposed on the inner side of a portion of the male and female sides 3a and 3b to be heat-sealed. Holes 5 are punched through the insertion tape 4 and the male side 3a and the female side 3b of the chuck 3 by a punch at regular intervals corresponding to a longitudinal sealing interval.
Heat seal bars 8 are then applied to the outer surface of the bag-forming films 2a and 2b at regular intervals corresponding to the longitudinal length of the bag 1 such that the heat seal bars 8 are orthogonal to the feeding direction of the bag-forming films 2a and 2b to seal the bags in the longitudinal direction thereof. As a result, a region of the lower surface of the bag-forming film 2a and that of the upper surface of the bag-forming film 2b are sealed. At the same time, in the chuck 3, a region of the male side 3a and a region of the female side 3b are sealed through the punched holes 5. These sealed regions correspond to a sealing region of both sides of the bag 1.
Heat seal bars 9 are applied to the outer surface of the longitudinally sealed bag-forming films 2a and 2b along the insertion tape 4 to seal them in the widthwise direction thereof. As a result, a region of the lower surface of the bag-forming film 2a and a region of the upper surface of the bag-forming film 2b are sealed, and a region of the male side 3a and a region of the female side 3b are sealed. The male-side chuck 3a and the female-side chuck 3b are not sealed because the insertion tape 4 is inserted between the inner surface of the portion to be sealed thereof. The longitudinal sealing may be carried out after the widthwise sealing terminates.
The center of the longitudinally sealed portion is then cut longitudinally with a cutter to separate the bag-forming films 2a and 2b into a plurality of bags.
However, the above-described conventional art includes the step of automatically and successively producing the chuck-provided bags 1. Thus, it is not easy to change the longitudinal and widthwise sealing lengths. In particular, once the longitudinal length of the bag 1 corresponding to the longitudinal sealing length is set, the equipment of a producing line is set. Thus, in the conventional method of producing the chuck-provided bag, it is difficult to change the longitudinal length of the bag 1.
To change the longitudinal length of the bag 1, it is necessary to remodel the equipment of the producing line which is a costly process. That is, in the conventional art, it is difficult to vary the longitudinal and widthwise lengths of the bag, thus limiting the ability to produce bags of differing sizes.
Preferred embodiments of the present invention provide a method of producing a compression preservation bag allowing longitudinal and widthwise lengths thereof to be varied as desired, thus enabling the production of bags with a wide variety of sizes.
According to preferred embodiments of the present invention, a method of producing a compression preservation bag includes the steps of forming a cylindrical bag body having a closed bottom made of a material of synthetic resin and having a mouth portion at one end thereof in a longitudinal direction thereof; and installing a closing means, made of synthetic resin and having a length corresponding to a length of the mouth portion of the bag body, for opening and closing the mouth portion of the bag on a region in the vicinity of the mouth portion of the bag body.
In the method of producing the compression preservation bag, the bag body is formed of a laminate film which is rectangular and flat. The closing means-installing step includes preparing a belt-shaped closing tape having one or more pairs of concavities and convexities to engage each other; engaging the concavities and convexities of the closing tape; forming the closing tape annularly by thermally fusing both ends of the closing tape in a longitudinal direction thereof, with the convexities engaging the concavities, and by cutting the closing tape to desired lengths in the longitudinal direction thereof; and thermally fusing the closing tape into an inner side of the bag body such that the closing tape is disposed in the vicinity of the mouth portion of the bag body.
The bag body is made of a laminate film or other suitable material. One end of the closing tape is thermally fused to the other end of the closing tape in the longitudinal direction thereof such that a length of one end of a non-fusing portion of the closing tape in a widthwise direction thereof is shorter than a length of the other end of the non-fusing portion in the widthwise direction thereof, and the shorter portion of the non-fusing portion is thermally fused into the vicinity of the mouth portion of the bag part such that the shorter portion of the non-fusing portion is disposed at an end of an open side of the mouth portion of the bag body.
It is effective to form a tapered portion at one end and the other end of the non-fusing portion of the closing tape in the longitudinal direction thereof such that the tapered portions incline symmetrically to make the non-fusing portion gradually smaller toward the end of the open side of the mouth portion of the bag body.
According to the method of producing the compression preservation bag of preferred embodiments of the present invention, the closing means for freely opening and closing the mouth portion of the bag body is produced separately, and installed on the inner side of the mouth portion of the bag body produced in advance such that the closing means is disposed in the vicinity of the mouth portion of the bag body. Thus, in the method of producing the compression preservation bag, the closing means can be installed on the mouth portion of the bag body at a desired length which is determined by desired longitudinal and widthwise lengths of the desired bag body.
Thus, unlike the convention art, in the method of producing the compression preservation bag, when the longitudinal length of the bag body is changed, it is unnecessary to remodel the equipment of a producing line. Thus, the method of the present invention allows the longitudinal and widthwise lengths of the bag body to be varied as desired, and therefore, allows for the production of a wide variety of bag body sizes.